THE FORMATION AND EMISSION MECHANISMS OF NOx IN CROP STRAWS AND COAL CO-COMBUSTION FLUIDIZED-BED COMBUSTOR

摘要

Our country is rich in biomass energy. It is the second great energy, only inferior to coal. Lots of research indicated that, mixing coal with biomass at certain proportion can reduce the emission of SO2 and NOx. The emission of NOx in fluidized bed combustion is low and the crop straws take up a lot in biomass. According to these points, we choose cornstalk and Heshan coal as fuel to do the experiment of co-combustion in the fluidized-bed combustor. First, make the fuel to standard sample, mix them at the proportion of 1:1 and 4:1. Then investigate the combustion characteristics on the STA 409C thermo balance analyzer separately. The NOX emission from co-combustion of biomass and coal were studied in a small lab-scale fluidized bed reactor, taking sorts of coals, excessive coefficient of the air and the co-combustion proportion into account. The data shows that the NOX emission of coal is higher than the crop straws’. As the temperature increasing, all fuel’s emission adds. Make the air/fuel equivalence ratio reach 1.2 and 1.4 by controlling the flow meter，the emission increased again. At last, measure the emission content with the mass fraction of 10% and 25%.The result indicated that the mixture of crop straws could reduce the NOx emission of coal combustion efficiently. As the proportion increasing, the effect gets more evident. Quick combustion and pyrolysis in the bottom of fluidized bed boiler produced a lot of volatile containing many reductive ions.